I had a semi-similar problem. The system was P4, 2GB RAM, dual 400G disk in RAID1 with raidframe. I copied images from a camera from CF, and would find corrupted JPGs. On investigating I found that the two copies on disk were different. One was usually right (different disks though), and the other had the IIRC 0x80 bit set on a number of bytes (10ish?) in some number of 512-byte sectors, typically only a few. Of course usually most files were correct on both disks. My memory is hazy, but I think I ran memtest86+ or something and couldn't get it to fail. I replaced the memory and all has been well ever since. I never had a lot of program core dumps, not enough to rise about the noise. I suspect that the voltage stress of the two disks writing at once messed up the memory, and also suspected my power supply at one time, but the memory swap fixed things.
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